(a) Field of the Invention
The present invention relates to an ultra-wideband (UWB) device design. More particularly, the present invention relates to a method for a local UWB radar system to generate ultra-wideband signals and design radiation drawings, the system being used for a security system for detecting an intrusion into a protection area.
(b) Description of the Related Art
In general, the important block of a radar type of device is a radio frequency (RF) unit in a like principle in which an ultrasonic wave output unit and a control wiring unit are important parts of an ultrasonic wave device and an infrared receiver and a control wiring unit are important parts of an infrared device. The RF unit includes an RF transmitter, a receiver, and a control device.
FIG. 1 shows a circuit diagram of a general radio signal transmitter. An operational characteristic of an ultra wideband frequency bandwidth is that the conventional format that does not use an output amplifier can be changed a little. For example, the documents disclosed in the Pulstech and Intel web sites may describe features of an output amplifier.
The transmitter characteristics determine important specifications of equipment such as the distance, safety for interference, intrusion performance, complexity, and price. For example, a frequency infrared band sensor is used to guard spaces in various buildings. The sensor is inexpensive but generates frequent false alarms because moving air flows at different temperatures in a guard area. RF components of microwave sensors at major roads are expensive. The greater the frequency is, the greater the price is. The microwave sensor has large input power.
The large input power is a characteristic of the ultra-wideband RF circuit. A method for solving the problem is to use a method for controlling RF module power appropriate for the UWB.
Various attempts for increasing the frequency in the used RF constituent elements are known. Particularly, one solution is Russian Patent No. 2188500 [3] for complementing the radar structure with a wave guide filled with a predetermined gas and a laser resource. In the case of outputting the laser, part of the gas is changed into plasma. The wavelength of the VHF range is divided to the plasma part while passing through the pipe, which generates VHF beam pulses with a length that is less than 10 ms. The above-noted solution is complex and expensive and hence its application range is very limited.
U.S. Pat. No. 5,889,497 [4] discloses an ultra-wideband output device, in which a pulse generator is connected to two horn antennas having different insulation characteristics and the beam pulse has a pulse generation speed with a range of 200 ps. The solution is generally used for a high-pressure device, which generates a bad influence on the degree and price of device elements.
U.S. Pat. No. 6,100,839 [5] discloses an improved pulse radar system, system for combining the functions of respective constituent elements so as to reduce the price and size of the system. Respective elements of an antenna array are proposed to be used as transmit antennas and receive antennas, and one ADC is used. However, this method fails to notice the fact in which the Q factor of the antenna is reduced in proportion to the enlargement of the operational frequency bandwidth. Therefore, the ultra-wideband sensor requires an ultra-wideband antenna having a great Q factor so as to guarantee the function of a signal generation circuit resonator. However the antenna used in [5] does not have the above-noted characteristics.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.